Telephotographic recording apparatus



Feb. l 1927. 1,615,979

R. HART TELEPHOTOGRAPHIC RECORD NG APPARATUS Zrzvezz tor; Russell Hart, per

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C TEL/EPHoTo 0 E 76' 77 /a D ""1 I Enz/enter;

Russell Harl?, ,ver

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A ttorney.

Patented Feb. l, 1927.

RUSSELL HAR'I, OF LOS ANGELES, CALIFORNIA.

TELEPHOTOGRAEHIC RECORDING APPARATUS.

Application led July 2,

' I My lnvention relates to telephotography, and its obJects are; first to provide means for receiving photo-modulated energy transmitted from a remote point, either by radio, 'wired radio, or. wired systems; second to afford facilities for the utilization of this energy for the reproduction of drawings, photographs, printedmatter, and the like; and, third, to-accomplish the above results by means of relatively simple and thoroughly dependable apparatus. Other objects and advantages of the invention will appear hereinafter. v y

It is to bel understood that, While I illustrate and describe herewith a preferred .means for accomplishing my objects, I do not limit myself to the specific forms and arrangements disclosed. 'Various changes andadaptations may be made therein withoutI departing from the' spirit of my invention ashereinafter claimed.

My objects are attained by means of the `apparatus illustrated in the accompanying drawings, which are to be considered as diagrammatic throughout, rather than strictly pictorial. In these drawings- Figure 1 is a side elevational `view of the photographing portion of my apparatus;

Figure 2 is a central longitudinal section of the same in elevation, and on a somewhat larger scale, the` section being taken on the line 2-2 of Fig. 3.

Figure 3 is a lan view shown partly in section on the lme 3- 3 of Fig. 2 and on the same scale as the latter.

Figure 4 is `a greatly enlar ed fragmentary view of the light modu ating target which, in the 'present illustrations, is shown mounted -upon the diaphragm of an ordinary telephone receiver \but may be attached to any .vibratile electro-operated device that is responsive to minute variations ofcurrent;

FigureF is a' much enlarged longitudinal sectionjof thel exposure portion of the apparatusin elevation:

Figure 6 is an enlarged cross section of a portion of the traversing mechanism;

Figure 7 is an enlarged elevation showing details of the adjustable shutter used for varying the visible lengt-h of the incandescent filament used as a light source;

. Figure 8'is a wiring diagram .illustrating one way in which the various electrical de- 1923. Serial No. 649,085.

vices which are employed in connection wit-h my invention may be connected up Figure 9 is a greatly magnified diagrammatic view of a small fragment of a tele-A photographic lm made by my device, illustrat-in the character of the record and how the e ects of light and shade aresecured;

Figure 10 is a view of ashort stri of the recorded film as thusproduced; an

Figure 11 is a greatly enlarged view of a ortion of the film illustrated in Fig. 10.

ISimilar reference numerals refer to similar parts throughout the several views.

Before. passing to a detailed description of the construction and operation of my invention it should be understood that its purpose is to photographically reproduce, as exactly as possible, an optical film used for transmitting purposes at a remote point.

The recording film used in the present invention is necessarily of the same length and width as the transmitting film, and each of these is made in the form of an endless beltembodying positive driving means in its construction. These two films are run simultaneously, and in perfect synchronism, at separated points. l

The synchronizing ofthe films may be conveniently accomplished by the use of syn# chronous motors connected' into the same power distribution system when this is feasible. Where the distance, or the conditions are such that it is not possible to' connect both motors into the same power distribution net work, the synchronizing may be effected in various ways known to those familiar with these arts. For example an alternating current wave, originated by the power system that operates the transmitting motor and synchronous therewith, may be sent out by radio lor wire line to the receiving station, and there amplified by therm'ionic devices to a strength suicient to run the receiving motor.

In av companion application, filed coincidently with this, I have disclosed means for photo-modulating electric energy waves by the use of an endless optical film having graphs thereon. The modulation is therein accomplished by causing a photo-sensitive modulating device to continuously traverse an image of the transmission lm in succesl sive closely spaced parallel lines which may endless flm. The -whole of the film surface is ultimately covered in this manner and the 'gra hs thereon may be considered as being divided into very narrow and closely spaced strips which are run past the modulating devlce in proper sequence for the purpose of modulating the outgoing energy wave in accordance with their instantaneous optical characteristics. The outgoing energy waves m'ay be transmitted either as radio, wired radio, or wired energy by methods explained in the .application referred to. f

The present invention. comprises a substantial reversal of the above process. The incoming photo-modulated energy waves are received by suitable devices and amplified when necessary. This modulated energy is then caused to proportionally vary the visible length of a tenuous light source whose image is focused upon a photo-sensitized film which is continuously moving in synchronism with the film being used .for transmitting. The image of the light source is continuously advanced transversely to the moving film so that the exposure when-completed constitutes a narrow helical band, of small pitch, around the recording film.

The simultaneous co 0perating processes of the sending and receiving apparatus allow of securing either a positive or negative record at the receiving end, depending upon the arrangement and characteristics of the photo-modulating devices used. Ordinarily a negative film will be used for transmitting', and a series connected selenium cell, or its equivalent, will be employed for modulating the transmitted energy. In this case the high lights of the original graph will correspond to opaque arcas on the transmitting negative film. These areas will allow very little light to fall upon the modulating device and the instantaneous value of the transmit-- ted energy will be low.I This small energy will have a proportionally small effectupon the modulator at the receiving end, and result in a correspondingly slight exposure of the receiving filmv aty that point. As a conseguence the development of this film will prouce a transparent area of high light, corresponding to the high light on'the original graph. A positive transmitting film may be used for producing alpositive recording film if either of the ytwo modulating devices has its photo-characteristics reversed as by niechanical or electrical arrangement.

The telephotographic receiving apparatus constituting the present invention, as herein illustrated, comprises a fixed upright exppsure cameraI 12 wherein the recording film lt 13 is mounted upon driving sprockets 14. The film itself is provided with sprocket perforations 15 at each edge. The spacing of these perforations is uniform 'and their number is the same as that of the transmitting film. `Spring constrained rollers 16 prevent the film belt from becoming disengaged from the sprockets in operation.

The film belt is mounted with its photosensitized surface outwaqd, and is caused to pass over the convex exposure plate 17 which is let into the side of the exposure camera box in such a manner that its apex is substantially flush with the outer surface of the box. This construction is shown most clearly in Fig. 5.

Idler drums 18, having axes transversely adjustable in slots 19, as by the wing nuts 20, are provided for regulating the tension on the film belt.

At the rear of the exposure camera, in line with its transverse axis, is a focusing tube 21 which ordinarily is closed by a cap 22. TheA purpose and use of this will be explained later.

The light modulating camera comprises a horizontal box structure 23 mounted upon a pair of V guides 24 in such a manner that it may be given a slow uniform motion transverse to its axis, by means of the feed screws 25. The mounting is such that one end of this camera may be moved transversely in very Aclose proximity to the face ofy the exposure camera, but not in actual contact therewith, since friction and vibration are' necessarily to be avoided. The -modulating camera has a fixedend tube 26,

opposite the exposure plate in the exposure camera. This tube is used for focusing, in a manner to be explained later on, and' also as a housing for the objective lens group 27and diaphragm 28.

At the opposite end of the modulating camera isa chamber 29, containing the light source and having an axial opening 30 in the dividing partition 3l. This opening may be variably closed by a pair of overlapping .slides controlled by thumb Screws 32 on the outside of-the camera. One of these slides, 33, is deeply indented as at 34, and in cooperation with the other slide 35 provides a.. rectangular/opening 36 of constant width and variable length. The edges of the slides constituting this opening are preferably beveled to a sharp edge, asindicated most plainlv in Fig. 7

For the source of light I prefer to employ a`special form of incandescent electric lamp shownat 37. This contains a thin lineal' filament 38 of tungsten. stretched between an axial terminal 39 and a transverse resilientterminal 40 adapted to maintain the filament in tension at all temperatures, and thereforey rectilinear. This lamp is mounted in a clamp 41 with its filament intersecting the axis of the camera at right angles. Means foradju-sting the angular position of the filament in its vertical plane are provided by the wing nut 42.

' phragm 45 o this receiver lcarries at its center a post'46, at the outer end of which is afiixed a sharp edged transverse target 47. Between the modulating deviceA and the light source there is a lens group 48, coaxial with the camera and mounted in such a manner that it may be'focused. A convenient means of mounting comprises the partition 49 and fixed tube 50, into which the lens housing may be slid and positioned by the set screw51.

' As indica-ted above,- the exposure camera 12-is fixedly mounted, while the modulating camera is vmounted on V guides so 'that it may be `slid transversely to its axis.- In order to maintain proper positioning'of the vcameras it is desirable to install them upon a substantial pedestal 52, of masonry, and in a location as free as possible from vibration. A synchronous motor 53 is attached to pedestal and serves to drive allof thefoperatig mechanism simultaneously and at roper relative and absolute speeds. .Thus .t e traversing of modulating camera 23'is accomplished through the me` diumof pinionr 54, spur` gear 55, shaft 56,

worms 57 and worm wheels 58. which are fixed upon feed screws 25. The film is rotated. by means of shaft 59, bevel Pinion 60, bevel gear` .61, bevel inion 62 and the'two bevel' piniols 63 driving the bevel ears 64. The latter are affixed to the shafts o sprockets 14.. Theratios of the several gear trains is so chosen that feed screws 25 make/one complete turn coincidently with one complete revolution of the film belt. The motor, as previously explained, is synchronized with the *mot-or of the remote transmitting device and its s eed is so chosen that the transmitting an recording films have the )same period of revolution.

The various electrical devices used with my present invention, aside from the motor y and light source, are diagrammatically indicated in Fig. 8. .This figure shows a typical arrangement of circuits for receiving modulated radio energy from a telephotographic sending station, and utilizing it for the modulation of light for recording purposes b v' the apparatus herein described. Conventional symbols are employed in this ffgnre.l and fit will. rea ily understood by those familiar with the radio art. Obvious- -ly other circuit arrangements might be employed for receiving radio` energy, and

I changes in the arrangement and use of stand- .cept'i'on of the ard `apparatus will be required for the remodulated energy by wired j radio, lo r wired systems. 'I he conditions will .a suitable tubular microscope is inserted in its place. Such a microscope is indicated in dotted lines at in Fig. 2, inserted in tube 76 21, where it is subsequently used for focusing a sharp secondary image of the filament j upon the. sensitized surface of film 13.

In order to accomplish the first step of the f focusing the modulating camera has to be moved a sufficient distance past camera 12 to allow-the microscope to be inserted in the tube 26. By the aid of the microscopethe razor edge of target 47 isthen brought up to the optical axis of the camera and adjusted. perpendicularly thereto. This is done bymoving the modulating telephone 43 in or out of tube 44 and tightening the set 'screw y. when Nthe target is correctly ositioned.

4The microscope is next careful y focused 90 uponthe razor edge and then, without dis.- turbing its adjustment, lens group 48 is moved in or out of its tube until an image of filament 38 appears perfectly sharp in the microscope.- Set screw 51 is then tightened,.95 the microscope is removed from tube 26,. and lens group 27 is replaced in that tube. A

The second step of the focusing consists in. placing the microscope inl tube 21and inserting a piece of exposed developed film-in camer 12, over the exposure plate, with its expose surface outward and in the position the recording film is to occupy. The

.microscope is then, accurately focused,

"group'27 is moved in or out of-its tube un- 110 til a' secondary image of the filament appears perfectly sharp in the microscope. Set screw 67 is then tightened and the focusing of the-device is complete.

The next step in the operation is to adjust orifice plates 33 and 35 so that the target just eclipses the secondaryimage of the fila-- ment when diaphragm 45 is in its normal po sition with no current flowing in the modulating device: and so as to shut off-as much as possible of the visible length of the filament without eclipsing the primary image above the razor edge when the .latter is in its retracted position with maximum current fiowingin the modulating device. The ob- 125 ject in this is to allow a sufiicient visible length of filament to permit the target to perform' its eclipsing function throughout the whole range of its vibrations; but at the same time it is desirable to cut off all strayr light rays so far as this is possible.`

The purpose of the small orifice 68 in diaphragm 28 is to further assist in blocking off stray light. In practice it is frequently desirable to use a. narrow slit at this point instead ofthe circular orifice depicted, and in. either case it must be carefully positioned so as not to shut off any portion ofthe secondary Iimage falling uponrthe recording film.

After completing the above steps the microscope is removed from tube 21, cap 22 is replaced, and an unexposed film belt 13 is placed inits proper position in exposure camera 12. Thereafter, assuming; that the electricall detecting and amplifying devices tion lof a very small image of a very thin luminous filament; the image being transverse to the direction of motion of the film, and varying in' length in consonance with the photo-modulated venergy sent out by the' transmitting station. The image is con-A tinuously moved 1n a dlrectlon transverse to the motion of the film so that the latter ultimately exposed in a helical band of varying width but uniform pitch. The successive bands do not overlap, but vary in width from nothing to .very nearly the pitchv of the helix, so that at times the exposed surfaces are only separated-by a minute space. The

pitch of the helix is also very small, being ordinarily from l to 2 one hundredths of an i inch. This pitch corresponds to the dis` v tance between the 'parallel lines, 69-in the magnified View of Fig. 9.

Then the target 47 completely eclipses the image of the filament there is no ex-- posure ofthe film and, after develo ment, the latter resents a transparent sur ace as at 70. Wien only aminute portion of the light from the filament is allowed to fall as an image upon the film, the latter is exposed in thin lines as at 69. As the photomodulated energyfrom the transmitting station increases, the target 47 is drawn further away from the optical 'axis of the camera, and a longer image of the filament l v is thrown upon the film. This results in broader exposed lines, asiat 71. Atl the in-A stant of peak transmitted energy, the exposed bands become relatively very wide bands, although in fact theydare as at 72, 72 and 74. When side by side, as at 73' in Fig. 9, these relatively wide slightly spaced, give the film the appearance of hav-I ing a solidly exposed area when viewed from a small distance.

Surface shading of the record is accomplished by varying the width of the bands in the manner just-described, from nothing toa width approximating the pitch. Horizontal lines, transverse to the record, /are produced by short lengths of wide bands side by side as at 73 and 74.

The pictorial effect that may be attained by this method of shading is illustratedin Fig. 10. Here the picture of the house is produced by `uniformly spaced parallel lines of differentiwidths. The end of the house is represented by fine lines and a pears as a light grey. The face of t e: chimney is made up of heavier lines of the same spacing and appears much darker. The shadow under the eaves at 75 appears still darker, as tlie component lines are still wider.y The joints between the stones of the-chimney appear white, since there are no exposure lines at all at those points. The letters at 76 appear to be solid black since the spacing between the lines is invisible at a short distance. This is also true of the chimney flue at 77,.l

If we were to magnify the upper portion of the film shown in Fig. 1Q we would` get the effect shown in Fig. 11. Here again, when viewed at a slight distance, the let-1 tering andthe chimney fiue appear to bev solid black, but acloser inspection shows that all the lines are, in fact, spaced.

The-construction and operation of my in- `vention will doubtless be clear from the foregoingdescription .and need not be further elaborated. It will be seen that it is applicable to the transmission of all graphical material. including drawin s, phot0- graphs, printed matter and the ike.A

I- claim:

v no

1. Tele-photographic recording apparatus comprising; an endless photo-sensitized. recordin film; means for imparting a uniform' he ical motion to the film; a linear light source; mea-ns forI projecting an image of said source transversely upon said film; and means for continuously varyin the length of said image proportionate y to transmitted photo-modulated energl 2. Tele-photographic recording apparatus comprising; an endless photo-sensitized recording film; means for imparting a uniform helical motion to the film; arectilinear i light source of relatively great tenuity; means Vfor projecting an, image ofl said -source transversely upon said opaque target responsive to .photo-modulated energy,` whereby the rays from` said source may be variably. eclipsed to alter ,the

film; and an i length 'of said image proportionately to c0- incldent changes in said energy. -f

3, Tele-photograhic recording apparatus com rising; an en less photo-sensitized refor imparting 'a unform helical motion to the iilm; a rectilinear A light source; means for projecting an image o saidsource transversely upon a plane; an opaque target vibratile to photo-modulated energy transverse y intersectin said image for modifying its visible 'length beyond the plane proportionately to colncident changes in said energy; and a lens intermediate the target and the lm adapted to focus a secary image of the first said image upon said film.

RUSSELL HART.

in said, plane having an edge 10 

